A well-known industrial process for the production of nitric acid is known as the Ostwald process. This process involves the oxidation of ammonia with oxygen over a platinum group catalyst, often platinum or a platinum/rhodium alloy, at a temperature above about 800 degrees C, sometimes as high as 1200 degrees C. The resulting gas stream contains nitric oxide, NO, and nitrous oxide, N.sub.2 O. (See Ind. Eng. Chem. Proc. Dev., 1962, 21, 73-79.) The NO is cooled in the presence of excess oxygen and NO.sub.2 is formed. The NO.sub.2 is reacted with water to form nitric acid. The N.sub.2 O does not readily react further, and in some process is released to the atmosphere. N.sub.2 O has recently been recognized as an ozone depletion gas and efforts are under way to reduce the amount of N.sub.2 O that is released to the atmosphere.
Handley U.S. Pat. Nos. 4,774,069 and 4,869,891 disclose process is for the production of NO by the oxidation of ammonia over a platinum group catalyst. Patent '069 points out that during the oxidation some platinum and rhodium are converted to oxides and the oxides are vaporized and unless captured are lost. In the '069 process, a catchment trap is installed subsequent to the oxidation chamber where the vaporized catalyst metal oxides are deposited and subsequently recovered.
Anseth et al. U.S. Pat. No. 5,314,673 discloses conversion of N.sub.2 O to nitrogen and oxygen by contacting the N.sub.2 O with a catalyst consisting essentially of nickel oxide and cobalt oxide on a zirconia substrate.